Nozzle



Dec. 15, 1942. R. STAHL 2,304,851

NozzIlE Filed March 25, 1940 INVENTOR A TTORNEYS'.

Patented Dec. 15, 1942 UNITED STATES APA'IHELN'T OFFICE NozzLEApplication March 25, 1940, Serial No. 325,835

7 Claims.

The present invention relates to .spray appliances, adapted to spraypaint, synthetic enamels and lacquers and the like, and in particularprovides an improved method of, and apparatus for, projecting suchmaterial in a partially or completely atomized stream and thereafterconverting this stream into an atomized spray 'of substantiallyelliptical or at crosssection. This application is a continuation inpart of applicants prior application Serial N 119,563, filed January 8,1937.

In spray appliances of the type to which the improvements of the presentinvention particularly relate, the material is conventionally projectedfrom the tubular tip of a material nozzle, which nozzle isconcentrically disposed within an outer or air nozzle. Air is caused toissue from the air nozzle in the form of a tube or envelope whichsurrounds the material stream. In certain instances, the flow ofmaterial is caused by the suction created by the issuance of thesurrounding air stream, and in certain other instances, the material iscaused to ow under externaliy applied pressure.

The air stream which surrounds the material stream commingles with thematerial 'and either partially or entirely atomizes it to thus produce aspray of generally circular cross-section. It has heretofore beenproposed to subject this partially -or entirely atomized substantiallycircular spray of material to the -impact of two opposed and forwardlyconverging jets of air, which serve to hatten the stream and in certaininstances to complete the 'atomization thereof.

The forwardly converging nature of the auxiliary ,-f-

air streams also serves to assist in projecting material spray forwardlyagainst the object to ce coated.

In utilizing spray appliances of this character,

the operating costs are materially affected by the amount of airrequired per unit volume of the material that is sprayed, and the highspraying rates now commercially demanded, by, for example, theautomobile manufacturers, has

able Values. The cost of the spraying operation is also materiallyaected by the degree of atomization thereof and by the uniformitythereof, it being appreciated that a spray which is incompletelyatomized, and is of non-uniform density throughout the cross-sectionthereof re- .':uits in an irregular sprayed surface, requiring iativelyexpensive subsequent manual rubbing sanding operations.

In extending the prior nozzle constructions to caused the air supplycosts to rise to objectionhigh spraying rates, it has been foundnecessary to materially increase the rates of iiow through the auxiliarynozzles. This is initially objectionable because of the increased aircosts, and is A ladditionally objectionable .-in that it has been .foundthat the streams vof thus increased intens-ity serve to deforrn thematerial stream 'or spray from fa flat or oval shape to a dumb-bellshape. In certain instances, it has been found that the material iscompletely divided into two separate streams. In addition, particularlywhere the material being sprayed is 'of a non-homogeneous character, andincludes nely divided particles of heavy materials such as are found invitreous enamels, the convergent air jets ilick an unduly large part ofthe heavy constituents of the material out of the carrier liquid. Thisaction causes an -objectionably large offspray, and also reduces thedesired heavy or Vsolid particle content of the material. Variousarrangements have been proposed with a view to overcoming thesetendencies, among which are included the provision of additionalauxiliary or supplemental air jets, which surround the previouslymentioned main or central air jets and cooperate with the convergentauxiliary -air jets. This expedient, as will be appreciated, materiallyincreases the required volume lof air, and complicates the structure byrequiring the provision of a multiplicity of additional jets.

It Ahas been found, in accordance with the present invention, that thediiliculties above mentioned, as welll as others, rmay be effectivelyovercome, and a gun produced which requires a materially lowerpercentage of air ow per unit Yof material sprayed, by introducedbailles in the baths of. the auxiliary and convergent air jets. Thesebellies serve the purpose of modifying the forms of the auxiliary jets,and cause them to reduce the material stream to accurate elliptical vorhat form without introducing either .the irregularities mentiond aboveor causing the undesirable iiicking from the stream of any 4heavyparticles which may be carried in the carrier liquid. In one form, thebail'les are so positioned that the auxiliary air jets, while deliectedthereby and modied as above stated, lie in generally coplanar relationto the mai-n material stream. In another form the baflles are so formedand positioned relative tothe auxiliary streams, that they deflect atleast a portion of each auxiliary air stream and cause these streams toseparate and Vform a supplemental envelope around the material stream. 4

y With the above and other considerations in present invention;

view, objects of the present invention are to provide an improved methodof and apparatus for producing an atomized flat spray of material, whichis economical and reliable; to provide such a method which includes theuse of one or more baflles interposed in the path of an auxiliaryflattening air stream; to provide such a method in which baffles areutilized to deflect and modify the form of each of a plurality ofauxiliary air streams, while maintaining them in co-planar relation tothe material stream; to provide such a method in which baffles areutilized which deect and modify at least a portion of the auxiliary' airstreams to cause them to ow in non-coplanar enveloping relationtransversely of the material stream; to provide such a structureutilizing baiiles formed-as a part of the supporting structure for theauxiliary air nozzles; to provide such a structure utilizing bafflesdisposed on either side of and projecting from the nozzle adjacent thematerial and primary air outlet thereof; and to provide such a structureembodying an improved mechanical relation Vbetween-the gun body, an airnozzle, and a material nozzle.

With the above and other, as well as more Fig. 2 is a view inperspective of the nozzle Istructure of the gun of Fig. 1;

Fig. 3 is a view in vertical longitudinal center section oiV the nozzlestructure Shown in Figs.

1and2; I Y

Fig. 4 is a View in end elevation, taken along the line 4 4 ofFig. 3;

Fig. 5 is a view corresponding generally to Fig.

A3, but illustrating the air and material streams;

Figs. 6 and 7 are diagrammatic views of jet forms, taken respectivelyalong the line 6,-6 of `Fig. 5 and 1-1 of Fig. 5;

Fig. 8 is a diagrammatic view of a material stream, illustrative of theimprovements of the Fig. 9 is a view in perspective of Ya nozzleconstruction embodying a modification of the invention;

Fig. 10 is a view in vertical longitudinal section of the nozzlestructure shown in Fig. 9;

Figs. 11 and 12 are diagrammatic views of air and material stream formstaken respectively `along the lines II-II and I2-I2 of Fig. 10; and

ally an air nozzle 20, hereinafter described in more detail; Va barrel22; a handle grip portion 24; a trigger 26; vand suitable material andair 'inlets 28 and 29. The nozzle 20 is removably secured to Vthe barrel22 by a connector or collar 30, and encloses the hereinafter describedmaterial nozzle. It will be appreciated that with the 'trigger 26 in theillustrated position, both the ,material and air inlets are closed off,and that,

in order to place the gun in operation, the trigger 26 may be swung in acounter-.clockwise direction as viewed in Fig. 1, the resultant degreeof open'- ing of the material inlet being adjustable by means of aconventional adjusting head 34. A

corresponding conventional adjusting element 32 is provided for the airinlet.

Referring more particularly to Figs. 3 and 4, the barrel 22 is bored toprovide a longitudinally extending material supply passage 40, and aparallel longitudinally extending air supply pasyenol of the barrel isprovided with two annular counterbores or recesses 44 and 45. The recess44 communicates through a valve opening 46 with the air supply passage42, and the recess 45 communicates therewith through a passage 4T; 'Iheeffective area of the valve opening 46 is disposed to be regulated by aneedle valve formed at the end of a valve rod 48, which, in turn, isdisposed to be actuated by an adjusting head 34 disposed exteriorly ofthe gun so as to permit the supply of air to the auxiliary air jets, tobe more fully described later, to be controlled so as to enable thepattern of the ejected spray to be varied. The supply of air to thepassage 42 is controlled by a valve (not shown) mounted within Vthe gunin a conventional manner, and this valve,

together with the valve controlling the paint sup'- ply, is controlledby thel trigger 26. The recess 44 forms a distributing chamber todistribute the air supplied through the passage 42 to each of two xhereinafter described a-uxiliary air nozzles B, provided in the horns 52of the nozzle 20, and the recess 45 forms a distributing chamber throughwhich air is supplied to the central or main air nozzle A.

The hollow or tubular material nozzle 54 is pro-v vided with anexternally threaded shank 60,' by "which itis secured within thecorrespondingly threaded outer end of the barrel 22, and is alsoprovided with an enlarged head 62, the external surface of which isconical. The outer end of the material nozzle 54 includes a taperedportion 64,

and terminates in a nozzle or tip, the side walls of Vwhich arepreferably of uniform internal diV` ameter and, define the materialnozzle M. The

conical end 68 of the needle valve 'l0 seats against the rear end of thenozzle M. The needle valve 10, as has been mentioned, is disposed foractuation by the trigger 26 of Fig. 1.

The inner face of the enlarged portion 62 of the material nozzle 54 isprovided with a pair of annular ribs T2 and 'I4 which bear againstthe.

outer end of the barrel 22. `The rib 14 abuts the portion 16 of thebarrel which lies between the annular recesses 44 and 45, and thusisolates these recesses from each other. The rib 'I2 bears against theportion 18 of the barrel 22.

The air nozzle 20 is in theform of an inwardly`V presented cup, theinner walls 9B of which are nozzle.

portioning of the parts is such that a chamber 92 is provided betweenthe inner surface of the air nozzle 20 and the outer end of the materialnozzle 54, which chamber communicates with the previously mentionedrecess 45 through a'plurality of longitudinally extending passages 94formed in the material nozzle 54. The walls`96 of the air nozzle 20,.which yare opposite the. tapered' Wall portions 64 ofthe materialnozzle, are correspond'- ingly taperedy and spaced therefrom. The-` Wallportion 9B terminates in a short section 981 the inner surface of whichisv preferably slightly convergent and, with the tip of the' materialnozzle, defines an annular nozzle or orice A through which a tube orenvelope of air maybe discharged around the stream of. material emittedthrough the opening M. The base-of the nozzle illl-v is pro'- Vvidedwith a shoulder 9i which is engaged by a flange 93 on the collar 30, toretainY nozzle 20 in assembled relation.

The means for providing the auxiliary jets of air which are utilized inthe present construction to control the form of the atomized materialstream, as well as to complete itsatomization, include the passages 50which extend longitudinally of the two diametrically opposed horns 52 ofthe air nozzle 2li', and a pair of convergent passages 100 whichcommunicate with the longitudinal passages 5i?, respectively, andterminate in nozzles B.

In order to modify the effect of the auxiliary streams of air, bafflesare introduced in the paths 5 thereof as previously mentioned, and inthe embodiment now being described, these bailies are formed as part ofthe horns 52. Each baille includes a surface 02 disposed as acontinuation of and at substantially the same angle as the corg.

responding convergent passage Hill. The inner surfaces of the bafflesare undercut, as indicated at E04, which undercutting produces an areaof relatively low pressure immediately behind each auxiliary jet of air.

The remaining mechanical features of the structure above described maybest be considered with reference to a description of the operation of`the unit. It will be appreciated that the material to be sprayed, andadmitted through the inlet 28 to the barrel passage 40, may be suppliedunder pressure, or that, alternatively, the discharge of material fromthe material nozzle M may be caused by the suction produced by theprimary air stream discharged through the air nozzle A. To open thenozzle M, the trigger 26 may be moved in a counterclockwse direction,asviewed in Fig. l, thus withdrawing the valve A,rod lil. This movementof the trigger also admits air to the longitudinal barrel passage 42 byopen*- ing the conventional air valve (not shown). The auxiliary airvalve' 46 is assumed to have already been adjusted to its properlyopened position, but it may, of course, be adjusted during operation ofthe gun to vary the pattern of the spray to suit r the desires of theoperator. The circuit for nozzle A extends from passage 42 throughpassage 41, around recess 45, passages 94, and thence through chamber $2to nozzle A. The circuit for' nozzle B extends through valve 46, aroundrecess 411:, and thence through passages 50' and |001.

In response -to the above action, a solidv sub'- stantially circularstream of material. in a liquid state is continuously emitted from thematerial nozzle M, which stream is` surrounded and enveloped by a tubeor envelope of air emitted from the circular air nozzle A.v As will beappreciated, the arrangement and proportioning of the air and materialnozzles and of the pressures at which the air and material streamsemerge from the corresponding nozzles are so proportioned that theenveloping and slightly convergent tube of air from the nozzle A acts toatomize the stream of material and transform it into a ne spray. In

-certain instances it is desirable to effect the complete atomization`by' the primary air stream, While Y in others', as in the present case;the atomization is' intensied and completed by the auxiliary airstreams.

It has heretofore been proposed to so arrange andv form the air nozzle,corresponding to the nozzle A in the present instance, that the primarytube orgenvelop'e of air acts to itself modify the 'shapeor pattern ofthe material stream, as well as to atomize this stream.. In the presentinstance, however, it is preferred to conne the function: of the airstream A to the atomization only andl rely solely on the auxiliary jetsto modify the pattern.

Concurrently with the flow of atomizedV material through the nozzle M,surrounded by the envelope of air from the nozzle A, and at a ratedetermined by the opening of the valve G6, as well as by the materialand air pressures, two auxiliary streams of air are discharged throughthe convergent nozzles B, as diagrammatically shown in Fig. 5, andimpinge upon the material stream at a point slightly beyond the point atwhich the atomizing effect of the primary air stream is begun. The twoauxiliary streams of air impinge upon the material stream atdiametrically opposed points and. have the effect of not only modifyingthis stream from its original circular form to the oval or ellipticalform shown in Fig. 8, but also to intensify the atomization of thematerial being discharged from the nozzle M. As will be appreciated, theprecise relation between the major and. minor axes of the oval b may becontrolled bythe relative intensities and volumes of the material streamand the two auxiliary air streams, and it is found in the practice ofthe present invention that this relation may be varied betweenrelatively wide limits.

As previously mentioned, nozzles heretofore made, of which the presentapplicant is aware, utilizing auxiliary` streams of air such as areemitted through the nozzle B in the present instance, have beenobjectionalole in that a tendency is present to deform the materialstream from the oval shape b of Fig. 8 to the dumb-bell shape shown indotted lines c in the same gure, when the volume of air admitted throughthe auxiliary nozzles is increased to the eXtent required to obtain thedesired l'iness of atomization particularly when spraying material of aheavy or a nonhomogeneous character and particularly where such materialincludes finely divided particles of heavy materials such as are foundin vitreous enamels. A tendency is also present, particularly whenutilizing material which includes relatively heavy solid particles, toflick an unduly large proportion of the solid particles out of thestream where the volume of air through the auxiliary nozzles is thusincreased. This action forms an undesirably large olf spray, and alsoreduces the proportion of the solid parti-cles and renders the spraynon-uniform ln cross-section.

These ldifficulties are entirely overcame in the practice of the presentinvention by the provision of the baille surfaces 02. As is showndiagrammatically in Fig. 6, the baille surfaces H12 act to relativelyreduce the intensity of and spread the streams of auxiliary air. Inpassing over the lower edges or lips of the baille surfaces U52, theauxiliary air streams are slightly bent inwardly and laterally spread asindicated in Fig. 5, and it is found in practice that after leaving thebaille surfaces, the auxiliary air streams may assume an oval shape 3 asshown in Fig. '7. In. certain cases, depending upon the precise shape ofthe olds or the like.

Vin'n'er edges of the baille surfaces',` the streams may assume thekidney shape indicated by the dotted line f in Fig.' 7. The baffles thusserve to modify the shape of the auxiliary streams and by'enlarging thecross sections thereof reduceY the relative rate of flow, andconsequently reduce the intensity with which they would otherwiseimpinge upon the material stream if'their volume was increased overconventional practice tothe point necessary tov obtain the desiredneness of atomization of heavy materials such as enamel- The materialstream is thus bathed, so to speak, inthe auxiliary air streams and isflattened thereby to oval form without introducing the irregularitiesindicated in Fig. 8, and without such intensity of ow as would causeundesirable flicking out of any solid particles in the material as wouldhappen in Vconventional vconstructions if the volume of flow through theauxiliary nozzles was increased to the desired ex-V tent. The Volume ofair through the auxiliary f B open, are undercut so that the auxiliarystreams of air are entirely unconned in the regionjbe-Y nozzles may thusbe increased to an extent, as

compared to conventional constructions, as to intensify the atomizationof the paint or like material ejected from the main nozzle toV obtain i;

the desired neness of material, without the dan-l ger of flickingparticles of solid material out of the character as small openings whichmight be constantly plugging up in service.

In the modified embodiment of the invention shown in Figs. 9 and 10,vthe baille surfaces |02 are replaced by baille surfacesY I which projectin diametrically opposed relationship from the outer end of the airnozzle, adjacent the axial center thereof. As shown in Fig. 11, theouter surface ||2 of each baffle ||0 is arcuate in form, and the breadthof each baille is substantially in excess of the diameter of the centralair nozzle A. The outerends of the bailles I |0 are disposed in thevpath of and intersect a certain portion of the auxiliary convergentstreams of air flowing through the nozzles B. The portions of theauxiliary streams which are not intercepted by the baille plates l0impinge upon the material stream and serve to flatten it. The portionsyof the lauxiliary streams which areV intercepted by the baffle plates|10 are deflected thereby and are caused to flow outwardly thereover, inthe manner indicated diagrammatioally in Fig, 11 and in an enlargedscalein Fig. 12. This outward or transverse flow kof air serves to draw thematerial ably such that the auxiliary streams impinge upon the materialstream at a point slightly beyond the point at which the atomizingeffect of the main or central air stream is initiated.

In the modified embodiment of the invention shown in Fig. 13, baillesare provided which are in the p'ath'ofY and are'imping'ed by theauxiliary streams of air discharged through the Vauxil-iary air nozzlesB, inthe same general relation asin the embodiment of Figs. 1 through 8.In

the embodiment-of Fig. 13, howeventhe nozzle" surfaces |22, throughwhich the nozzle openings tween each nozzle opening B and thecorresponde ing baille |20. It will be recalledthat in the embodiment ofFigs. l `through 8, the auxiliary streams .of air travelalong the baillesurfacesV lare entirely unconfined from the time they leave Y the nozzleopenings B until they impinge upon the baffle surfaces |20, the effectof the. baille sur# faces |20 is vsomewhat more pronounced.

Except in the structural respects just mentioned, the embodiment of Fig.13 may, and preferably does, duplicate the structure of Figs. ,1 through8, and it will be understood that except in the respects noted, theoperation of the two embodiments is also the same. That is to say, thatpart of each auxiliary air stream which im-V pinges upon orpassesdirectly over a baille surface is deflected, in the plane of thepaper, as viewed in Figs. 5 and 13, for example, toward the materialnozzle. In -other words, the width Vof the air streams in thejust-mentioned plane is increased, thereby correspondingly increasingthe length of the zone in which the auxiliary air streams are effectiveto act upon the material stream.

Although specic structural embodiments Vof the invention and specicmethods of practicing it have been described, it will be appreciatedthat various modifications in the form and arrangement of thestructures, and various changes in the methods, may be made within thespirit and scope thereof.

What is claimed is:

1.' In a nozzle structure for a device of the class described, thecombination with a material nozzle for'forwardly projecting a materialstream, and a pair of auxiliary air nozzles for directing auxiliary airstreams against said material stream transversely thereof, of a pair ofdiametrically opposed baille platesv disposed at opposite sides of andin forwardly extending relation to said material nozzle, said auxiliaryair nozzles being positioned radially outwardly of said baffle plates,said baille plates acting to break the associated air streams in twoparts flowing substantially in a plane paths respectively of said airstreams and being z positioned radially inwardly of .said nozzles.

3. In a nozzle structure for a device of the class described, thecombination of a material nozzle for forwardly projecting a materialstream, a pair of auxiliary air nozzlesV fordirecting air streamsagainst saidV material stream transversely thereof,

said auxiliary nozzles being so positioned that the axes of said air andmaterial streams are substantially co-planar, and baille means disposedbetween said auxiliary and material nozzles, said baille means havingsurface areas positioned for direct impingement by said air streams,said baille means being abruptly cut away adjacent the forward auxiliaryair streams to modify the form of the auxiliary air streams before suchair streams impinge upon the material stream.

4'. In a nozzle structure for a device of the class described, thecombination of a material nozzle for forwardly projecting a materialstream, a pair of auxiliary air nozzles for directing air streamsagainst said material stream transversely thereof, said auxiliarynozzles being so positioned that the axes of said air and materialstreams are substantially co-planar and baille means disposed betweensaid auxiliary and material nozzles, said baflle means having surfaceareaspositioned for direct impingement by said air streams, said baillemeans being abruptly cut away adjacent the forward edges of said areasso that such edges are relatively sharp, said nozzle structure beingsoconstructed and arranged that said auxiliary air streams are unconned inthe region between the corresponding nozzle opening and thecorresponding baille means, and said baille means acting to modify theform of the auxiliary air streamsI before such air streams impinge uponthe material stream.

5. In a nozzle structure for a device of the class described, thecombination of a material nozzle for forwardly projecting a materialstream, a pair of auxiliary air nozzles for directing air streamsagainst said material stream transversely thereof, said auxiliarynozzles being so positioned that said air and material streams aresubstantially coplanar, and baille means positioned between eachauxiliary air nozzle and the material nozzle for direct impingement bythe corresponding air stream, each baille means comprising a surfaceforming a continuation of the corresponding air nozzle opening andhaving a relatively sharply undercut forward edge over which thecorresponding air stream flows after said impingement, said baillesurfaces and said auxiliary air nozzles being so constructed andarranged as to be ineffective to interfere with expansion of thecorresponding air stream transversely of said plane, and each saidbaille surface serving to widen the corresponding air stream in saidplane.

6. In a nozzle structure for a device of the class described, thecombination of a material nozzle for forwardly projecting a materialstream, a pair of auxiliary air nozzles for directing air streamsagainst said material stream transversely thereof, said auxiliarynozzles being so positioned that said air and material streams aresubstantially coplanar, and baille means disposed between said auxiliaryand material nozzles, said baille means having surface areas positionedlfor direct impingement by said air streams, ,said baille means beingabruptly cut away adjacent the forward edges of said areas so thatsuchedges are relatively sharp, said baille means including a baille surfacein the line of flow of each air stream, and said nozzle structure beingso constructed and arranged that each air stream is unconned in theregion between the corresponding baille surface and the correspondingair opening.

7. In a nozzle structure for a device of the class described, thecombination of a material nozzle for forwardly projecting a materialstream, at least one auxiliary nozzle positioned radially outwardly fromthe axis of the material nozzle for directing an air stream against saidmaterial stream transversely of the latter, and baille means disposedbetween said auxiliary and material nozzles and in the plane of saidauxiliary and material nozzles, said baille means having a surface areapositioned for direct' impingement by said air stream, said baille meansbeing abruptly cut away at the forward edge of the said area so thatsaid edge is relatively sharp, said nozzle structure being soconstructed and arranged as to not interfere with expansion of said airstream transversely of said plane in the regiori between the auxiliarynozzle opening and the baille` means, and

said baille means acting when impinged by said auxiliary air stream tomodify the form of the air stream before such air stream impingesuponthe material stream. jl

` RODOLPI-IE STAHL.

